Picture this: the car won't start, the immobilizer light is on the dashboard, or the vehicle simply "doesn't see" the key. There could be several reasons for this—ranging from a dead key battery to a loss of synchronization between the immobilizer unit and the engine control unit (ECU).
Common Causes
- a dead battery in the key fob or a damaged transponder chip
- loss of synchronization between the engine control unit and the immobilizer (often happens after disconnecting the car battery)
- a faulty reader antenna or immobilizer unit
- replacing the ECU, after which the new module doesn't "recognize" the existing keys
What to Do
Don't try to push-start the car or repeatedly disconnect the 12V battery—this only makes the desynchronization worse. The right approach is computer diagnostics: we read the trouble codes, check module communication, and then resynchronize or program the keys using professional equipment.